A very good point.
First, we still iterate through this page, so feedback as such is highly valuable.
There're obviously different ways to order things, like by 'logical' order, or by usage frequency (the former would typically be better for new users, the latter for experienced ones).
The summary section moved to the bottom due to its 'concluding' nature - it's a summary.
Obviously shortly after the change users are far more likely to mistakenly type into the payment info section instead of the summary section.
The real question is which is the optimal order for all. I'll do a quick research and if it makes sense to move the summery section above the payment information section, we shall do that.